title: MS/MS fragmentation-guided search of TMG-chitooligomycins and their structure-activity relationship in specific β-N-acetylglucosaminidase inhibition.
abstract: The reducing tetrasaccharide TMG-chitotriomycin (1) is an inhibitor of β-N-acetylglucosaminidase (GlcNAcase), produced by the actinomycete Streptomyces anulatus NBRC13369. The inhibitor shows a unique inhibitory spectrum, that is, selectivity toward enzymes from chitin-containing organisms such as insects and fungi. Nevertheless, its structure-selectivity relationship remains to be clarified. In this study, we conducted a structure-guided search of analogues of 1 in order to obtain diverse N,N,N-trimethylglucosaminium (TMG)-containing chitooligosaccharides. In this approach, the specific fragmentation profile of 1 on ESI-MS/MS analysis was used for the selective detection of desired compounds. As a result, two new analogues, named TMG-chitomonomycin (3) and TMG-chitobiomycin (2), were obtained from a culture filtrate of 1-producing Streptomyces. Their enzyme-inhibiting activity revealed that the potency and selectivity depended on the degree of polymerization of the reducing end GlcNAc units. Furthermore, a computational modeling study inspired the inhibitory mechanism of TMG-related compounds as a mimic of the substrate in the Michaelis complex of the GH20 enzyme. This study is an example of the successful application of a MS/MS experiment for structure-guided isolation of natural products.
authors.affiliation: Okayama Prefectural Technology Center for Agriculture, Forestry and Fisheries, Research Institute for Biological Sciences (RIBS), 7549-1 Kibichuo-cho, Kaga-gun, Okayama, 716-1241, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Usuki
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Yuya
authors.initials: Y
authors.lastname: Kumagai
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Nitoda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kanzaki
authors.forename: Tadashi
authors.initials: T
authors.lastname: Hatanaka
mesh_terms: D000118:Acetylglucosaminidase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D001236:Aspergillus oryzae / Q000187:drug effects / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009840:Oligomycins / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D021241:Spectrometry, Mass, Electrospray Ionization; D048372:Streptomyces coelicolor / Q000187:drug effects / Q000201:enzymology; D013329:Structure-Activity Relationship; D053719:Tandem Mass Spectrometry
chemical_list: D004791:Enzyme Inhibitors; C559536:N,N,N-trimethylglucosaminium; D009840:Oligomycins; D000118:Acetylglucosaminidase; D005944:Glucosamine